This disclosure relates to methods for recovery of hydrocarbons from subterranean wells employing one or more well treatment fluids.
Compositions and methods useful for modifying the near wellbore region of a hydraulic fracture—proppant flowback control in particular—are not all successful. Many proppant flowback control methods involve the addition of a resin, a tackifying material, fibers, or deformable particles into the sandpack with the intent of increasing the particle-particle (and particle-wall friction) and preventing the individual sand or proppant grains from becoming entrained into the fluid phase and produced back into the wellbore. Although these methods can successfully control proppant flowback, it often comes at the cost of reduced fracture conductivity since these added proppant flowback control materials may take up space in the porous pack, occupy some of the pore throats, or reduce the proppant pack permeability.
Due to changes in formation fluid flow rate, formation fluid composition and phase, the need for proppant flowback control can diminish with time. Often proppant flowback control is needed only during the first few days to weeks after formation of a hydraulic fracture, when the flow rate of formation fluid is the highest. Frequently the proppant pack experiences its greatest stress during the first few hours of clean-up, when the broken fluid is flowing back at a high rate and fracture closure has not reached equilibrium. Also, many gas wells have steep decline curves—very high rates of gas production during the first few months falling off as the formation pressure drops.
Therefore, there remains a significant and as yet unmet need in the art for methods of treating subterranean formations intersected by a wellbore, and methods of completing a wellbore, that control proppant flowback employing a changeable additive or additives having good proppant flowback control properties but has minimal long-term damage to the proppant pack hydraulic conductivity.